Apple has released two firmware updates to address several issues with its 27-inch iMac systems. The first update (27-inch iMac EFI FW Update 1.0) is recommended for all 27-inch iMac models using Intel Core i5 or i7 processors and fixes a couple of bugs. One flaw causes high processor utilization while playing audio via the headphone output jack, and another prevents the display backlight from turning on after the machine is powered on.
The second update (27-inch iMac SMC Firmware Update 1.0) targets an unspecified compatibility issue with Target Display Mode, a feature that is only available on 27-inch iMacs and allows the machine to be used as a secondary display via its Mini DisplayPort connector.
In somewhat related news, Apple has also issued Security Update 2010-003 for Snow Leopard (6.5MB), Leopard Client (218.6MB), and Leopard Server (379.5MB). Additionally, Server Admin Tools 10.6.3 (236MB) has been pushed out to the public.